Non-uniform artificial turf infill

ABSTRACT

An artificial turf simulating grass including a layer of dispersed non-uniform, polyvinyl chloride-based particulates having non-symmetrical shapes and different sizes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. provisionalapplication No. 62/742,539 filed Oct. 8, 2018, which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to artificial turf, and particularly toturf infill comprised of polymer particles, granules or pellets.Artificial turf is typically used for sports and athletics surfaces, butmay also be employed in other applications to simulate lawns and grasssurfaces, such as playground turf, synthetic laws, landscapes, privateinstallations, parks, commercial surfaces, municipal grounds, testinggrounds and the like.

Artificial turf generally includes synthetic fibers or filaments thatare tufted into a woven material with an adhesive backing that holds thefibers or filaments to simulate blades of grass as an upright syntheticgrass layer. Natural and/or synthetic particulates, such as granules andpelletized matter, including for example one or more of rubbers, vinyls,sand, and a variety of polymers, are typically dispersed within theupright synthetic grass layer as infill, often referred to as turfinfill. The type of infill provides performance characteristics to theartificial turf, such as shock absorbency, ball rebound, friction, ballrolling, weather resistance, and other traits specific to a particularsynthetic turf construction.

Conventional synthetic infill materials are generally uniform in shapeand size, such as synthetic infill of rubber, polymers, and similarmaterials that have the same spherical and cylindrical shape and size.U.S. Pat. Pub. No. US 2017/0233956 (the '956 Publication), incorporatedherein by reference in its entirety, describes that infill pelletscomprised of polyvinyl chloride (PVC) may be extruded and cut andprovided in a number of different shapes (such stars, polygons, hearts,and triangles) to improve interlocking traction and performancecharacteristics of the artificial turf. Like other conventional infillmaterials, the '956 application contemplates only uniform regular shapesand sizes of infill.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide improvements beyondtraditional infill that has regular shapes with generally uniform sizesfor infill particulate material. The present invention provides fornon-uniform infill pellets, granules or particulates comprised of PVC inan installation of artificial and synthetic turfs.

In embodiments of the invention PVC infill pellets and granules that aredispersed as infill in artificial turf installation have a variety ofmultiple sizes and irregular shapes, such as non-symmetrical shapes, toimpart improved performance characteristics to the artificial turf. Inspecific embodiments, such shapes include seed-like and droplet-likeshapes of different sizes. In further embodiments, such shapes includegenerally elliptic, ovate and obovate shapes. In still furtherembodiments such shapes include generally biconvex and asymmetricallyoval shapes (such as pumpkin seed-type and sunflower seed-type shapeswith generally pointed ends). In still further embodiments such shapesinclude generally teardrop/lachrymiform shapes. It various embodimentsany combinations of the foregoing different shapes can be provided withone another in various sizes as PVC infill granules, pellets andparticulates in an artificial turf installation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph of PVC infill pellets having different irregularshapes and different sizes in an embodiment of the invention.

FIG. 2 is a front view of a multi-hole extrusion die having differentsize holes for producing PVC infill pellets as shown in FIG. 1 in anembodiment of the present invention.

FIG. 3 is a front partial and magnified view of a multi-hole extrusiondie of FIG. 2 in an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in one embodiment in FIG. 1, PVC-based particulates 5 forartificial turf infill include a variety of non-uniform shapes andsizes. Generally, the particulates are irregular, such asnon-symmetrical shapes that resemble seeds and/or liquid droplets.PVC-based particulates 5 preferable for use in embodiments of theinvention include such PVC granules and pellets having compositions asdescribed in the '956 Publication, which is incorporated herein byreference. Further, the PVC-based particulates 5 may be manufactured inaccordance with conventional extrusion, pelletizing and molding methods.In embodiments of the invention, PVC granules and pellets may bemanufactured in accordance with methods described and/or referenced inthe '956 Publication.

In one embodiment, an extrusion die 20 as shown in FIGS. 2 and 3 may beused to produce PVC particulates 5 having multiple shapes and sizes inaccordance with the invention. It will be appreciated by those skilledin the relevant art of extruding, pelletizing and molding of PVCcompositions that the manufacturing parameters, such as run rate,temperature settings, and the like, for optimally producing PVC pellets,granules and particulates as in the present invention will depend on anumber of factors such as particular machine being used, the particularenvironment for manufacturing, the precise composition of PVC-basedmaterial, and similar variables. Arriving at desirable results as partof the manufacturing process for PVC-based infill shaped and sized inaccordance with the invention will therefore be well within the scope ofa person skilled in the relevant art and are not considered critical tothe present invention.

In one embodiment shown in FIGS. 2 and 3, the extrusion die 20 includesnumerous rings of different sized holes, such as a ring of first holes30, a ring of second holes 32, a ring of third holes 34 and a ring offourth holes 36. The holes are of different sizes so that a variety ofnon-uniform irregularly shaped and various-sized PVC particulates 5 maybe produced. It will be appreciated that configurations for holes,number of holes, shapes of holes, distance between holes and alignmentof holes (whether rings, grids or other patterns) may be varied from thedepicted embodiment while still supporting the production of irregular,non-uniform and various-sized PVC particulates 5 in other embodiments ofthe invention.

In embodiments of the invention, the use of irregular, non-uniform andvarious-sized PVC particulates 5 imparts improved performancecharacteristics to artificial turf as compared to uniform particulatesdisclosed in the '956 application. In the Tables I-III test resultssubsequently described, uniform PVC-based infill particulates used inartificial turf according to the '956 application are referenced as“20s/50TPE_PriorArt”, non-uniform PVC infill particulates that have notbeen subjected to wear simulation used in artificial turf according toan embodiment of the present invention are referenced as “70/30Pre-Wear”, and non-uniform PVC infill particulates used in artificialturf that have been subjected wear simulation machine with aLisport-brand wear machine are referenced as “70/30 Post-Wear”.

To compare performance characteristics, each 20s/50TPE_PriorArt, 70/30Pre-Wear and 70/30 Post-Wear particulates were provided in artificialturf and subjected to the following described tests. The20s/50TPE_PriorArt particulates were provided in an artificial turf testsystem of 20 lbs sand/50 lbs thermoplastic elastomer (TPE) over 2½″Turf. The 70/30 Pre-Wear particulates were provided in an artificialturf test system of 4.97 lbs per sq. ft. PVC, 2.13 lbs per sq. ft. Sand,2.25″ slit film turf and no pad. The 70/30 Post-Wear particulates wereprovided in an artificial turf test system of 4.97 lbs per sq. ft. PVC,2.13 lbs per sq. ft. Sand, 2.25″ slit film turf and no pad and subjectedto 20,000 cycles of a Lisport wear machine.

The following laboratory tests were conducted on each of theparticulates/artificial turf system samples. Technical guidelines of theSynthetic Turf Council (STC) are incorporated herein by reference. ENreferences are to European Standards which are also incorporated hereinby reference.

Force Reduction (%)—(STC Advanced Artificial Athlete Protocol test)Measures the impact absorption provided by a surface to a player underfoot as they run. A lower value describes a surface that is harderunderfoot. The results are compared to the STC performance guidelines of57% to 68% for a Community Field and 62% to 68% for a Stadium Field.

Vertical Deformation (mm)—(STC Advanced Artificial Athlete Protocoltest) Measures the amount a surface compresses as an athlete runs acrossit. This value is often related to speed of play and surface stability.The results are compared to the STC performance guidelines of 6 mm to 11mm for a Community Field and 6 mm to 10 mm for Stadium Field. VerticalDeformation typically will reduce over time as a field receives use.

Energy Restitution (%)—(STC Advanced Artificial Athlete Protocol test)Measures the energy returned as a percentage of the energy of applied.This can be thought of as the springiness of the surface. This valuerelates to the feel underfoot as well as the speed of play. Althoughthis measurement is not a part of the official standard, it is a usefulmeasure. The recommended range is 20% to 50%.

ASTM F355A Gmax/HIC Impact Attenuation (Flat Faced Drop Missile) (G's(Units of Gravity))—The ASTM F355A Impact Hardness is the officialdevice/method for assessing the hardness of synthetic turf athleticfields. It is used to gauge impact attenuation based on a predeterminedhead/body impact. This is a 20 Ib “missile” with a tri-axialaccelerometer dropped from a height of 24 in. The STC recommends thatthe Gmax values be less than 165.

EN 1177—HIC Impact Attenuation (Hemispherical Drop Missile) (CriticalFall Height (m))—The EN 1177—Impact attenuating play surfacingdetermination of critical fall height method is similar to the methodcommonly used for assessing playground surfacing in the United States.Internationally it is the primary method for both synthetic turf andplayground surfacing. This device calculates the Head Injury Criteria(HIC). This is used to gauge the probability of head injury potentialresulting from a surface impact. This device is a hemispherical 10 lb“missile” with a tri-axial accelerometer. The hemisphere is dropped from(4) different heights to determine the height at which the HIC would be1000. This height is referred to as the critical fall height. It isrecommended that the critical fall height values be greater than 1.3meters.

Rotational Resistance—EN15301 (Newton Meters (n))—Rotational Resistancemeasures the interaction between the cleat sole and the surface relatingto the ability of a player to change direction. Higher values can relateto a surface that resists the rotation of a foot when a player ischanging direction and increase the potential for lower extremityinjury. STC guidelines recommend the results being 30 n to 45 n.

Vertical Ball Rebound—EN 12235 (Meters (m))—Measures how high the ballbounces when falling vertically onto a synthetic turf field. A ball isreleased from 2 m and the height of its rebound from the surface iscalculated. The ball is first calibrated on a level concrete surface to1.35 m. STC recommends from 0.60 to 0.85 m.

Following Tables I-III provide the test results, conducted indoors, foreach of the compared particulates in the respective artificial turfsystem:

TABLE I 20s/ 70/30 70/30 TEST UNITS 50TPE_PriorArt Pre-Wear Post-WearForce Reduction % 66 59 57 Vertical Def mm 9 8 7.9 Energy Restit % 23 2626 355A “Flat” Gmax G 108 133 137 355A “Flat” HIC 269 374 401 CriticalFall Height m 1.2 1 1 Rotational n 30 32 30 Resistance Ball Rebound m0.9 0.92 0.70

TABLE II Relative 70/30 Pre- Absolute Diff./ % Difference TEST UNITS 20s/50TPE_PriorArt Wear Difference Comment (Decimal) Force Reduction % 6659 Increase Decrease 0.106 7% over 10% Vertical Def mm 9 8 DecreaseDecrease 0.111 1 mm over 10% Energy Restit % 23 26 Increase Increase0.130 3% about 13% 355A “Flat” G 108 133 Increase Increase 0.231 Gmax 25about 23% 355A “Flat” HIC 269 374 Increase Increase 0.390 105 about 40%Critical Fall m 1.2 1 Decrease Decrease 0.167 Height 0.2 m over 15%Rotational n 30 32 Increase Increase 0.067 Resistance 2 n over 5% BallRebound m 0.9 0.92 Increase Increase 0.022 0.02 m about 2%

TABLE III Relative 70/30 Pre- 70/30 Post- Absolute Diff./ % DifferenceTEST UNITS Wear Wear Difference Comment (Decimal) Force Reduction % 5957 Decrease Decrease 0.15254 2% of 15% Vertical Def mm 8 7.9 DecreaseDecrease 0.13750 0.1 mm over 10% Energy Restit % 26 26 None None 0.000355A “Flat” G 133 137 Increase Increase 0.03008 Gmax 4 3% 355A“Flat”HIC374 401 Increase Increase 0.07219 27 7% Critical Fall m 1 1 None None0.000 Height Rotational n 32 30 Decrease Decrease 0.06250 Resistance 2 nabout 6% Ball Rebound m 0.92 0.79 Decrease Decrease 0.14130 0.13 m about14%

The results of tests set forth in Tables I-III indicate that embodimentsof the invention using PVC infill pellets and granules having a varietyof multiple sizes and irregular shapes, such as non-symmetrical shapes,that are dispersed as infill in artificial turf installations impartimproved performance characteristics to the artificial turf overconvention artificial turf installations.

Various embodiments of the invention have been described. It will,however, be evident that various modifications and changes may be madethereto, and additional embodiments may be implemented, withoutdeparting from the broader scope of the exemplary embodiments as setforth in the claims. This specification is to be regarded in anillustrative rather than a restrictive sense.

What is claimed is:
 1. An artificial turf comprising synthetic filamentsor fibers simulating grass adhered to a backing and an infill having alayer dispersed as a layer of non-uniform, polyvinyl chloride-basedparticulates between the filaments or fibers, wherein the particulatesinclude non-symmetrical shapes and different sizes.
 2. The artificialturf of claim 1, wherein the particulates are at least one of pelletsand granules.
 3. The artificial turf of claim 2, wherein theparticulates include at least three different sizes.
 4. The artificialturf of claim 3, wherein at least some of the particulates include anelliptic shape.
 5. The artificial turf of any claim 3, wherein at leastsome of the particulates include an ovate shape.
 6. The artificial turfof claim 3, wherein at least some of the particulates include an obovateshape.
 7. The artificial turf of claim 3, wherein at least some of theparticulates include a biconvex shape.
 8. The artificial turf of claim3, wherein at least some of the particulates include an asymmetricallyoval shape.
 9. The artificial turf of claim 3, wherein at least some ofthe particulates include a lachrymiform shape.
 10. The artificial turfof claim 3, wherein the particulates include a plurality of differentshapes selected from the group consisting of an elliptic shape, ovateshape, obovate shape, biconvex shape, asymmetrically oval shape, andlachrymiform shape.
 11. The artificial turf of claim 2, wherein at leastsome of the particulates include an elliptic shape.
 12. The artificialturf of claim 2, wherein at least some of the particulates include anovate shape.
 13. The artificial turf of claim 2, wherein at least someof the particulates include an obovate shape.
 14. The artificial turf ofclaim 2, wherein at least some of the particulates include a biconvexshape.
 15. The artificial turf of claim 2, wherein at least some of theparticulates include an asymmetrically oval shape.
 16. The artificialturf of claim 2, wherein at least some of the particulates include alachrymiform shape.
 17. The artificial turf of claim 2, wherein theparticulates include a plurality of different shapes selected from thegroup consisting of an elliptic shape, ovate shape, obovate shape,biconvex shape, asymmetrically oval shape, and lachrymiform shape. 18.The artificial turf of claim 1, wherein the particulates include aplurality of different shapes selected from the group consisting of anelliptic shape, ovate shape, obovate shape, biconvex shape,asymmetrically oval shape, and lachrymiform shape.
 19. The artificialturf of claims 18, further comprising a layer including sand underlyingthe layer of polyvinyl chloride-based particulates.
 20. The artificialturf of claim 1, further comprising a layer including sand underlyingthe layer of polyvinyl chloride-based particulates.